python - python 函数不返回任何内容

Question

我对 Python 很陌生。我正在尝试编写一个执行以下操作的函数，并在代码的 future 部分中重用该函数:(该函数的作用):

• 求两个列表元素之间的余弦值
• 将值添加到列表中并计算平均值
• 将平均值附加到列表
• 返回手段列表

然后我想根据上述函数返回的列表进行计算。但是，该函数(即 knearest_similarity(tfidf_datamatrix))不会返回任何内容。第二个函数(即threshold_function())中的打印命令不显示任何内容。有人可以看一下代码并告诉我我做错了什么吗？

def knearest_similarity(tfidf_datamatrix):
    k_nearest_cosineMean = []
    for datavector in tfidf_datamatrix:
        cosineValueSet = []
        for trainingvector in tfidf_vectorizer_trainingset:
            cosineValue = cx(datavector, trainingvector)
            cosineValueSet.append(cosineValue)
        similarityMean_of_k_nearest_neighbours = np.mean(heapq.nlargest(k_nearest_neighbours, cosineValueSet))    #the cosine similarity score of top k nearest neighbours
        k_nearest_cosineMean.append(similarityMean_of_k_nearest_neighbours)        
    print k_nearest_cosineMean
    return k_nearest_cosineMean


def threshold_function():  
    mean_cosineScore_mean = np.mean(knearest_similarity(tfidf_matrix_testset))
    std_cosineScore_mean = np.std(knearest_similarity(tfidf_matrix_testset))
    threshold = mean_cosineScore_mean - (3*std_cosineScore_mean)
    print "The Mean of the mean of cosine similarity score for a normal Behaviour:", mean_cosineScore_mean #The mean will be used for finding the threshold
    print "The standard deviation of the mean of cosine similarity score:", std_cosineScore_mean  #The standstart deviation is also used to find threshold
    print "The threshold for normal behaviour should be (Mean - 3*standard deviation):", threshold
    return threshold

编辑

我尝试为要使用的函数定义两个全局变量(即 tfidf_vectorizer_trainingset 和 tfidf_matrix_testset)。

#fitting tfidf transfrom for training data
tfidf_vectorizer_trainingset = tfidf_vectorizer.fit_transform(readfile(trainingdataDir)).toarray()

#tfidf transform the test set based on the training set
tfidf_matrix_testset = tfidf_vectorizer.transform(readfile(testingdataDir)).toarray().

但是 threshold_function() 中的打印命令如下所示:

 The Mean of the mean of cosine similarity score for a normal Behaviour: nan
The standard deviation of the mean of cosine similarity score: nan
The threshold for normal behaviour should be (Mean - 3*standard deviation): nan

编辑2我发现 k_nearest_cosineMean 中的第一个值是 nan。删除该值后，我设法获得有效的计算。

Answer 1

在threshold_function()的第一行中，您调用knearest_similarity(tfidf_matrix_testset)，但是您从未定义tfidf_matrix_testset是什么。您也在第二行中执行此操作。在第三行中，您使用第二行的输出。给 tfidf_matrix_testset 一个值。